Thai director and installation artist Apichatpong Weerasethakul has steadily made his way from exclusively receiving a highly specialized form of cinephilic admiration for his plethora of experimental shorts and structurally ambitious features to global status as one of the most enthrallingly cryptic filmmakers working today. His recent popularity mainly stems from his 2009 Palme d’Or win for “Uncle Boonmee Who Can Recall His Past Lives.” Although an established auteur years before “Uncle Boonmee,” that last movie most clearly defined his far-reaching aesthetic of loopy existential storytelling filtered through Thai folklore and other mystical conceits. Weerasethakul’s new hourlong experimental feature “Mekong Hotel,” cobbled together from ideas for another unrealized project, reaffirms the filmmaker’s appeal by simply arranging the same core elements into a distinctly odd collage.

According to the director, “Mekong Hotel” takes its inspiration from a story Weerasethakul originally wrote for a movie called “Ecstasy Garden” with an utterly batty premise. Weerasethakul’s initial idea involved an alien vampire ghost who also happens to be the mother of a young woman unaware of her supernatural lineage. In the original plot, the mother’s appetite gets the best of her and she devours her kin in the midst of the younger woman’s romancing of a local teen boy.

“Mekong Hotel” sort of follows this trajectory without exactly spelling it out; The movie contains scenes of rehearsals for “Ecstasy Garden” in the bedrooms and balcony of the titular hotel in northeastern Thailand, where the Mekong River flows majestically by with a lyrical coherence not unlike the experience of taking in Weerasethakul’s movies.

Shot on video with a free-associative style that moves between scripted and non-fiction material, the backstory of “Mekong Hotel” might place it in the tradition of documentaries about botched film projects like “Lost in La Macha” or “Hearts of Darkness,” but rather than chronicling a production history, Weeresethakul boils his original idea down to its strangest ingredients. A master of slowly cultivating atmosphere even within the framework of this concise running time, the director threads a mellow acoustic guitar tune through the duration of the movie to establish a peaceful tone that grows in its hypnotic effect, echoing the movie’s transition into a bizarre plane.

A prolonged discussion about the “pob ghost,” an invented carnivorous species Weerasethakul first heard about in his youth, sets the stage for some of the weirder circumstances that follow, including the mother feasting on the entrails of her sleeping daughter and a monologue in which one of the characters comes to accept his future reincarnation as a horse (and maybe, after that, some insects). Once you get used to Weerasethakul’s anything-goes rhythm, it’s easy enough to follow him into the realm of science fiction — when it turns out a wiry machine enables one of the hotel residents to sever his soul from his body. Somehow, the transition fits the scenario, which glides from moment to moment as if Weerasethakul himself possessed such a machine.

The mellow soundtrack often accentuates the setting’s tranquil qualities, but it just as easily plays against it with abrupt cuts to a character caked in blood — echoing the memorable arrival of the Ghost Monkey in “Uncle Boonmee.” Just when the movie slows down, it throws another irreverent twist into the frame, then gradually teeters off in favor of a tidy resolution. Never thrilling or transcendent, “Mekong Hotel” still inches toward profundity.

Despite its mysterious nature, the ploy of “Mekong Hotel” is transparent: Weerasethakul appears in the opening scene taking notes. From the outset, he’s a comforting presence — as if there to assure viewers that, no matter what happens, he has a handle on the situation. And through its lingering set of images and soul-searching monologues, he does: No mind-altering fever dream on the level of “Uncle Boonmee,” the doodles for ideas in “Mekong Hotel” still show that, even unfinished, Weerasethakul’s world is worth a return visit.

Criticwire grade: B

HOW WILL IT PLAY? Too brief and non-linear for any kind of extended theatrical release, “Mekong Hotel” could benefit greatly from availability online; it could also find eager crowds at cinephile-oriented screening series like New York’s Film Comment Selects.